org.apache.hadoop.io

Class SetFile.Reader

java.lang.Object

org.apache.hadoop.io.MapFile.Reader

org.apache.hadoop.io.SetFile.Reader

All Implemented Interfaces:

Closeable, AutoCloseable

Enclosing class:

SetFile

public static class SetFile.Reader
extends MapFile.Reader

Provide access to an existing set file.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.io.MapFile.Reader

MapFile.Reader.Option

Constructor Summary

Constructors

Constructor and Description
Reader(FileSystem fs, String dirName, Configuration conf) Construct a set reader for the named set.
Reader(FileSystem fs, String dirName, WritableComparator comparator, Configuration conf) Construct a set reader for the named set using the named comparator.

Method Summary

Modifier and Type	Method and Description
WritableComparable	get(WritableComparable key) Read the matching key from a set into key.
boolean	next(WritableComparable key) Read the next key in a set into key.
boolean	seek(WritableComparable key) Positions the reader at the named key, or if none such exists, at the first entry after the named key.

Methods inherited from class org.apache.hadoop.io.MapFile.Reader

close, comparator, createDataFileReader, finalKey, get, getClosest, getClosest, getKeyClass, getValueClass, midKey, next, open, reset

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Reader

public Reader(FileSystem fs,
              String dirName,
              Configuration conf)
       throws IOException

Construct a set reader for the named set.

Parameters:

fs - input FileSystem.

dirName - input dirName.

conf - input Configuration.

Throws:

IOException - raised on errors performing I/O.

Reader

public Reader(FileSystem fs,
              String dirName,
              WritableComparator comparator,
              Configuration conf)
       throws IOException

Construct a set reader for the named set using the named comparator.

Parameters:

fs - input FileSystem.

dirName - input dirName.

comparator - input comparator.

conf - input Configuration.

Throws:

IOException - raised on errors performing I/O.

Method Detail

seek

public boolean seek(WritableComparable key)
             throws IOException

Description copied from class: MapFile.Reader

Positions the reader at the named key, or if none such exists, at the first entry after the named key. Returns true iff the named key exists in this map.

Overrides:

seek in class MapFile.Reader

Parameters:

key - key.

Returns:

if the named key exists in this map true, not false.

Throws:

IOException - raised on errors performing I/O.

next

public boolean next(WritableComparable key)
             throws IOException

Read the next key in a set into key.

Parameters:

key - input key.

Returns:

Returns true if such a key exists and false when at the end of the set.

Throws:

IOException - raised on errors performing I/O.

get

public WritableComparable get(WritableComparable key)
                       throws IOException

Read the matching key from a set into key.

Parameters:

key - input key.

Returns:

Returns key, or null if no match exists.

Throws:

IOException - raised on errors performing I/O.